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OBJECTIVE: Military personnel has a large prevalence of back pain, especially those involved in patrolling routines, as they wear heavy protective equipment. Patrolling includes long periods of sustaining the protective equipment in a sitting or in a motor vehicle (motorcycle or car). Thus, understanding spinal loading of military police officers after patrolling by car (CAR; n = 14), motorcycle (MOT; n = 14), and administrative (ADM; n = 14) routines is relevant to establish preventive strategies. METHODS: The torque of the trunk and working and anthropometric characteristics were assessed to explain spinal loading using stature variation measures. Precise stature measures were performed before and after a 6 h journey (LOSS) and 20 min after a resting posture (RECOV). The trunk extensor (PTE BM-1 ) and flexor (PTF BM-1 ) muscles' isometric peak torque were measured before the working journey. RESULTS: The LOSS was similar between CAR and MOT (4.8 and 5.8 mm, respectively) after 6 h of patrolling. The ADM presented the lowest LOSS (2.8 mm; P < .05). No changes in RECOV between groups were observed (P > .05). Vibration may explain the greater spinal loading involved in patrolling in comparison to the ADM. A GLM analysis revealed that BMI was the only explanatory factor for stature loss. No independent variables explained RECOV. The ability of the trunk muscles to produce force did not influence LOSS or RECOV. CONCLUSIONS: Military police officers involved in patrolling may require greater post-work periods and strategies designed to reduce the weight of the protective apparatus to dissipate spinal loading. The external load used in patrolling is a relevant spinal loading factor.

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The aim of this study was to describe the intersegmental coordination and segmental contribution during intermittent vertical jumps performed until fatigue. Seven male visited the laboratory on two occasions: 1) the maximum vertical jump height was determined followed by vertical jumps habituation; 2) participants performed intermittent countermovement jumps until fatigue. Kinematic and kinetic variables were recorded. The overall reduction in vertical jump height was 5,5%, while the movement duration increased 10% during the test. The thigh segment angle at movement reversal significantly increased as the exercise progressed. Non-significant effect of fatigue on movement synergy was found for the intersegmental coordination pattern. More than 90% of the intersegmental coordination was explained by one coordination pattern. Thigh rotation contributed the most to the intersegmental coordination pattern, with the trunk second and the shank the least. Therefore, one intersegmental coordination pattern is followed throughout the vertical jumps until fatigue and thigh rotation contributes the most to jump height...

"Fadiga em salto vertical não afeta a coordenação intersegmental e contribuição segmental." O objetivo deste estudo foi descrever a coordenação entre segmentos e suas contribuições durante saltos verticais intervalados realizados até a fadiga. Sete indivíduos visitaram o laboratório em duas ocasiões: 1) foi determinada a altura máxima do salto vertical e realizada familiarização com saltos verticais; 2) participantes realizaram saltos verticais em contramovimento até a fadiga. Foram coletadas variáveis cinemáticas e cinéticas. A altura do salto vertical reduziu 5,5% e duração do movimento aumentou 10%. O ângulo da coxa no instante de reversão do movimento aumentou durante o exercício. A fadiga na sinergia do movimento não influenciou na coordenação intersegmental. Acima de 90% da coordenação entre segmentos foi explicada por um padrão coordenativo. A rotação da coxa foi o que mais contribuiu com o padrão coordenativo, seguido pelo tronco e perna. Portanto, em saltos verticais realizados até a fadiga, a coordenação intersegmental é mantida e a rotação da coxa tem maior contribuição na altura do salto...

"Fatiga salto vertical no afecta a la coordinación entre segmentos y la contribución segmentaria." El objetivo fue describir la coordinación entre los segmentos y sus contribuciones durante los saltos verticales realizadas hasta la fatiga. Siete sujetos visitaron laboratorio dos ocasiones: 1) determinó la máxima altura en el salto vertical y amistad con los saltos verticales; 2) participantes completaron saltos verticales contramovimento la fatiga. Se recogieron las variables cinemáticas y cinéticas. La altura del salto vertical disminuyó 5,5% y la duración del movimiento se incrementó 10%. El ángulo del muslo en instante de inversión del movimiento aumentó durante ejercicio. No hubo efecto de fatiga en sinergia de movimiento para la coordinación de movimientos. Más del 90% de coordinación entre sectores ha sido explicado por un patrón coordinativo. La rotación del muslo fue mayor contribuyente la coordinación de movimientos, seguido por tronco y piernas. En los saltos verticales realizados hasta la fatiga se mantiene coordinación entre segmentos y rotación del muslo tiene mayor contribución en altura del tacón...

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Back pain treatment in water has been commonly used although there is little evidence about its effects. One purported advantage for exercise is the reduced loading due to the buoyant force. The purpose of this study was to compare stature change, as a marker of spinal loading, after sitting in aquatic and dry land environments. Fourteen asymptomatic volunteers had their stature measured in a precision stadiometer, before and after a bout of physical activity and during a recovery period either sitting in water (head out of water immersion; HOWI) and sitting in a chair on land (SITT). Stature loss following exercise was as expected similar in both groups (SITT=89.2+/-5.4% and HOWI=86.5+/-8.1%; p=0.33). When stature recovery was compared between the water and land environments, HOWI (102.2+/-8.7%) showed greater recovery than SITT (86.5+/-6.3%) after 30 min (p<0.05). These results suggest that HOWI facilitated more rapid stature recovery through lower spinal loading and supports use of this technique to reduce spinal loading during recovery.

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This study aimed to analyse the effects of a single stretching exercise session on a number of gait parameters in elderly participants in an attempt to determine whether these exercises can influence the risk of fall. Fifteen healthy women living in the community volunteered to participate in the study. A kinematic gait analysis was performed immediately before and after a session of static stretching exercises applied on hip flexor/extensor muscles. Results showed a significant influence of stretching exercises on a number of gait parameters, which have previously been proposed as fall predictors. Participants showed increased gait velocity, greater step length and reduced double support time during stance after performing stretching exercises, suggesting improved stability and mobility. Changes around the pelvis (increased anterior-posterior tilt and rotation range of motion) resulting from the stretching exercises were suggested to influence the gait parameters (velocity, step length and double support time). Therefore, stretching exercises were shown to be a promising strategy to facilitate changes in gait parameters related to the risk of fall. Some other gait variables related to the risk of fall remained unaltered (e.g., toe clearance). The stable pattern of segmental angular velocities was proposed to explain the stability of these unchanged gait variables. The results indicate that stretching exercises, performed on a regular (daily) basis, result in gait adaptations which can be considered as indicative of reduced fall risk. Other studies to determine whether regular stretching routines are an effective strategy to reduce the risk of fall are required.

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The purpose of this study was to determine a resting interval between countermovement jumps (i.e., volleyball spikes) that allows the maintenance of maximal jumping performance. Ten male volleyball players (1.85 +/- 0.05 m, 77.2 +/- 10.6 kg, 21.6 +/- 5.3 years) performed 6 experimental jumping sessions. In the first and sixth sessions, maximal countermovement jump height was measured, followed by submaximal countermovement jumps to the point of volitional fatigue. The number of countermovement jumps was used as a reference to test the effect of rest period between volleyball spikes. From the second to fifth experimental sessions, 30 maximal volleyball spikes were performed with different resting periods (i.e., 8, 14, 17, and 20 seconds) followed by countermovement jumps. Between the 15th and 30th spikes, the blood lactate concentration and heart rate were measured. Because the performance on the first and sixth sessions was the same, no training effects were noticed. During the 8-second resting interval set, the lactate concentration increased significantly between the 15th and 30th spikes (i.e., from 3.37 +/- 1.16 mmol to 4.94 +/- 1.49 mmol); the number of countermovement jumps decreased significantly after spikes compared to those performed without a previous effort (i.e., from 23 +/- 7 jumps to 17 +/- 9 jumps); and these variables were significantly correlated (r = -0.7). On the other hand, the lactate concentration and number of countermovement jumps were stable across the other resting intervals, without a heart rate steady state. The results indicate that an adequate resting period between spikes allowed participants to achieve a lactate steady state in which the performance was maintained during the exercise. These findings show that resting intervals between 14 and 17 seconds, typical during volleyball matches, are indicated to use in volleyball spike drills due to their capacity to maintain maximal jumping performance.

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